Average high temperature and rainfall for San Juan in August. © Scott S. Bateman

San Juan weather in August is the hottest of the year. It also has a high risk of rain.

The San Juan cruise port is a popular port of call for eastern Caribbean cruises. Its popularity is the result of a convenient location in the Caribbean as well as major tourist attractions such as Old San Juan.

San Juan Temperatures in August

San Juan temperatures in August have an average high of 89 degrees Fahrenheit or 31 Celsius, according to the U.S. National Weather Service. Nighttime low temperatures average 77 degrees Fahrenheit or 25 Celsius.

August temperatures are the highest of the year along with June, July, September and October. By comparison, daytime temperatures reach a low point of 83 degrees Fahrenheit or 28 Celsius in January.

Water temperatures during the month will hover in the high 70s to low 80s Fahrenheit depending on the time of day. They feel comfortable and sometimes balmy in August.

Rainy Season in August

This video explains Caribbean weather in August and which islands are the best and worst to visit for weather. Full-Screen Version | YouTube Caribbean Channel

August rainfall in San Juan historically is the highest of the year along with September through November with an average of five to six inches each month, according to the U.S. National Weather Service.

August is the third official month of the annual Caribbean hurricane season. It begins in June and goes through November. By comparison, San Juan rainfall from January through April averages about two inches a month.

It also rains more often in August than earlier in the year. The total days with rain is an average of 15 in August compared to eight to nine days from February through April.

San Juan weather in August is risky for vacationers because of more rain than usual. Anyone planning a Caribbean vacation in the summer that might include San Juan should consider going in June rather than August. July usually has less rain than August but more than June.

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